1. Field of the Invention
The present invention relates to a high speed downlink packet access (HSDPA) and, more particularly, to a power control method of shared control channel for high speed downlink shared channel (HS-SCCH).
2. Background of the Related Art
In general, a wireless system of third generation partnership project (3GPP) proposes a new high speed downlink shared channel (HS-DSCH) in order to support a high speed packet data service. The HS-DSCH is used in a system following a Release 5 that specifies a high speed downlink packet access (HSDPA) among the technical specifications of 3GPP.
Unlike a W-CDMA system of the existing 3GPP Release 99/Release 4, the HS-DSCH uses a short transmission time interval (TTI) (3 slot, 2 ms). Thus, the HS-DSCH has been devised to transmit a high speed user data to different users every 2 ms sub-frame, and uses diverse modulation code sets (MCS) in order to support a high data rate.
In order for a user equipment (UE) to receive a user data, a shared control channel for HS-DSCH (HS-SCCH) and a dedicated physical channel (DPCH) should be constructed. The HS-SCCH, a physical channel, is a type of a downlink common control channel to support the HS-DSCH. HS-SCCH is used to transmit a UE ID-related control information so that the UE can receive the HS-DSCH transmitting a high speed user data. The user equipment monitors HS-SCCH to recognize whether there is a data to be received by itself and receives a user data transmitted through HS-DSCH by using the UE ID-related control information. At this time, the UE ID-related control information is transmitted through each frame (2 ms) of HS-SCCH. The UE ID-related control information is generated by a node B (a base station) to which a cell transmitting HS-DSCH belongs, and transmitted to the UE through HS-SCCH.
The control information transmitted through HS-SCCH is roughly divided into transport format and resource related information (TFRI) and HARQ related information. The TFRI includes a channelization code set during a HS-DSCH TTI, a modulation scheme, a transport block set size and a transport channel identity. The HARQ related information includes a block number and a redundancy version or the like. In addition, a UE ID (identification) is transmitted through HS-SCCH.
However, as described above, power control schemes for HS-SCCH are inefficient. Accordingly, an inter-cell interference is increased and a node B power is not effectively used. Thus, there is a long felt need for improved power control for control channels of mobile communication systems.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.